If cosA=cos B, then when does A=B? (Always, sometimes, never, infinite etc).
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No. Counterexample: If you work on the interval , then
So what is the answer.. Never or sometimes?
it is always the same when it is a sign identity since would just be a reflection of off the x axis then example:
Last edited by bigwave; Feb 4th 2010 at 01:10 PM. Reason: latex
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